For now i made a custom item class that looks like this :
public class ModTemplateItem extends SmithingTemplateItem {
private static final Formatting TITLE_FORMATTING;
private static final Formatting DESCRIPTION_FORMATTING;
private static final String TRANSLATION_KEY;
private static final Identifier EMPTY_ARMOR_SLOT_HELMET_TEXTURE;
private static final Identifier EMPTY_ARMOR_SLOT_CHESTPLATE_TEXTURE;
private static final Identifier EMPTY_ARMOR_SLOT_LEGGINGS_TEXTURE;
private static final Identifier EMPTY_ARMOR_SLOT_BOOTS_TEXTURE;
private static final Identifier EMPTY_SLOT_HOE_TEXTURE;
private static final Identifier EMPTY_SLOT_AXE_TEXTURE;
private static final Identifier EMPTY_SLOT_SWORD_TEXTURE;
private static final Identifier EMPTY_SLOT_SHOVEL_TEXTURE;
private static final Identifier EMPTY_SLOT_PICKAXE_TEXTURE;
private static final Identifier EMPTY_SLOT_INGOT_TEXTURE;
private final Text baseSlotDescriptionText;
private final Text additionsSlotDescriptionText;
private final List<Identifier> emptyBaseSlotTextures;
private final List<Identifier> emptyAdditionsSlotTextures;
private static final Text STARLIGHT_UPGRADE_TEXT;
private static final Text STARLIGHT_UPGRADE_APPLIES_TO_TEXT;
private static final Text STARLIGHT_UPGRADE_INGREDIENTS_TEXT;
private static final Text STARLIGHT_UPGRADE_BASE_SLOT_DESCRIPTION_TEXT;
private static final Text STARLIGHT_UPGRADE_ADDITIONS_SLOT_DESCRIPTION_TEXT;